For drone enthusiasts and professionals, choosing the right Electronic Speed Controller (ESC) firmware is as important as selecting the hardware itself. Two dominant firmware platforms have emerged in the FPV and drone industry: AM32 and BLHeli_32. Both represent significant advancements over earlier firmware like BLHeli_S, offering enhanced features, better performance, and improved configurability. This technical comparison examines their architectural approaches, performance characteristics, and suitability for different applications.
Understanding these differences is crucial when selecting components for your drone build or when evaluating ready-to-fly systems. The choice between AM32 and BLHeli_32 affects everything from tuning flexibility to compatibility with modern flight controllers and protocols.
BLHeli_32 is the proprietary, closed-source successor to the widely popular BLHeli_S firmware. Developed by a small team, it was designed specifically for 32-bit ARM processors, offering significant performance improvements over its 8-bit predecessor. BLHeli_32 gained rapid adoption due to its backward compatibility with existing tuning practices and its association with established ESC manufacturers.
AM32 (short for Another 32-bit firmware) emerged as an open-source alternative to BLHeli_32. Initially created to support a wider range of microcontroller architectures, AM32 has grown into a fully-featured firmware platform with active community development. Its open-source nature allows for greater customization and transparency, appealing to developers and advanced users who want full control over their ESC behavior.
BLHeli_32 is designed specifically for ARM Cortex-M0 and M4 processors from specific manufacturers. This focused approach allows for optimized performance on supported hardware but limits compatibility with other microcontroller families.
AM32 takes a more inclusive approach, supporting multiple processor architectures including ARM Cortex-M0/M3/M4 and even some RISC-V implementations. This broader hardware support makes AM32 particularly attractive for custom ESC designs and niche applications.
The closed-source nature of BLHeli_32 means users must trust the developers' optimization decisions. Updates and new features come exclusively from the original development team, with limited community input into the direction of the firmware.
In contrast, AM32's open-source codebase allows anyone to examine, modify, and contribute to the firmware. This transparency enables advanced users to understand exactly how their ESCs operate and even develop custom modifications for specialized applications.
Both firmwares offer rapid startup times compared to older 8-bit alternatives, but subtle differences exist:
- BLHeli_32: Typically initializes in 1-2 seconds, with consistent timing across different hardware implementations.
- AM32: Initialization time varies more depending on the specific processor and configuration, generally ranging from 1-3 seconds.
The core motor control algorithms represent one of the most significant differences between the two platforms:
BLHeli_32 employs a refined version of the algorithms that made BLHeli_S successful, optimized for 32-bit processing. The result is smooth, predictable motor control with excellent low-RPM stability.
AM32 offers multiple algorithm options, including traditional sine-wave commutation and more advanced space-vector modulation techniques. This flexibility allows users to select the algorithm that best matches their specific motors and flying style.
Both firmwares support high PWM frequencies (up to 48kHz or higher), but their implementation differs:
- BLHeli_32: Uses fixed frequency options with high resolution, providing clean signals that reduce motor heating.
- AM32: Offers more granular frequency control and adaptive frequency modes that can adjust based on throttle position or motor load.
BLHeli_32 supports:
- Bi-directional DShot (including DShot300/600/1200)
- Traditional PWM and Oneshot
- Basic telemetry data (RPM, temperature, voltage)
AM32 supports all BLHeli_32 protocols plus:
- CAN bus communication (enabling distributed ESC architectures)
- Extended telemetry parameters
- Real-time tuning parameter adjustments
BLHeli_32 Configuration:
- Proprietary configurator software (Windows-only)
- Limited number of adjustable parameters
- Straightforward interface suitable for most users
AM32 Configuration:
- Multiple configurator options including cross-platform tools
- Extensive parameter adjustments
- Command-line interface for advanced users
- Real-time parameter monitoring and adjustment
Both firmwares include comprehensive protection against over-temperature, over-current, and desynchronization. However, their implementation approaches differ:
- BLHeli_32: Uses conservative default settings with limited user adjustment of protection thresholds.
- AM32: Allows users to customize protection thresholds and responses, providing flexibility for specialized applications where standard protections might be too restrictive.
Most modern flight controllers work well with both firmware platforms, but some distinctions exist:
- BLHeli_32: Excellent compatibility with Betaflight and other mainstream flight controller software. Plug-and-play experience for most users.
- AM32: Requires more careful configuration but offers deeper integration possibilities, especially with flight controllers that support CAN bus communication.
Both firmwares work with standard brushless motors used in drones, but their performance with unconventional motors differs:
- BLHeli_32: Optimized for standard drone motor configurations (12-14 poles, typical Kv ranges).
- AM32: Better support for unusual motor configurations (high pole counts, very low or high Kv values) due to its more flexible configuration options.
At Noonefly, we conducted extensive testing of both firmware platforms before selecting AM32 as the foundation for our ESC product line. Our decision was based on several key factors:
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Customization Flexibility: As an open-source platform, AM32 allows us to implement custom optimizations specifically for our hardware designs. We can fine-tune algorithms to match our power stage characteristics and thermal management systems.
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Future-Proof Architecture: AM32's support for emerging communication protocols like CAN bus aligns with our vision for next-generation drone power systems. This positions our products for compatibility with future flight controller architectures.
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Community-Driven Development: The active AM32 developer community ensures continuous improvement and rapid response to emerging requirements. We contribute to this ecosystem while benefiting from collective innovation.
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Transparency and Trust: Open-source firmware allows our customers to verify the safety and reliability of our ESC software. This transparency builds trust, especially important for commercial and industrial applications.
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Performance Consistency: Our testing showed that with proper configuration, AM32 delivers equal or superior performance to BLHeli_32 across our entire product range, from compact 20A ESCs to high-power 110A units.
- You prioritize plug-and-play simplicity
- Your application uses standard components and flying styles
- You prefer established, commercially supported software
- Rapid setup is more important than maximum configurability
- You need customization for specialized applications
- You value open-source transparency and community development
- Your project involves unusual motor configurations or communication requirements
- You're building systems that might benefit from CAN bus integration
- You prefer Noonefly's optimized implementation with manufacturer support
- Use the manufacturer-recommended settings as a starting point
- Adjust motor timing based on your specific motor's specifications
- Enable bidirectional DShot for the best performance with modern flight controllers
- Keep protection settings at default unless you have specific reasons to change them
- Start with the Noonefly factory configuration for your specific ESC model
- Experiment with different motor control algorithms to find the best match
- Consider enabling CAN bus if your flight controller supports it
- Take advantage of the extensive telemetry data for fine-tuning
- Join the AM32 community forums to learn from other users' configurations
Both firmware platforms continue to evolve:
BLHeli_32 is expected to focus on:
- Improved user experience through simplified configuration
- Enhanced compatibility with emerging flight controller features
- Refined default settings for specific application profiles
AM32 development is likely to emphasize:
- Expanded processor architecture support
- More sophisticated motor control algorithms
- Enhanced safety and diagnostic features
- Tighter integration with open-source flight controller projects
The choice between AM32 and BLHeli_32 represents more than just a firmware selection—it reflects different approaches to drone technology. BLHeli_32 offers a polished, user-friendly experience optimized for mainstream applications. AM32 provides greater flexibility, transparency, and customization potential, particularly valuable for specialized applications and users who want deeper control over their equipment.
At Noonefly, our commitment to innovation and customer empowerment led us to embrace AM32. We believe that providing our customers with open, customizable technology fosters innovation and allows them to achieve optimal performance for their specific needs. Whether you're a recreational pilot, competitive racer, or commercial operator, understanding these firmware differences will help you make informed decisions about your drone's power system.
